Unit - 6 Exploring Android’s Content Providers

Lesson Plan: Unit - 06
Subject: P15A2AAD - Android Application Development
Topic of Study: Exploring Android’s Content Providers
Grade/Level: Master of Computer Applications
Objective: Understand the component of Android’s Content Providers
Time Allotment: 55 Minutes

• Exploring Androids Content Providers
• A content provider manages access to a central repository of data.
  
• Content providers can provide a way to share data with other apps.
• Content providers are the standard interface that connects data in one process with code running in another process.
• Exa.
  
• Advantages of content providers:
• Content providers offer granular control over the permissions for accessing data.
• You can use a content provider to abstract away the details for accessing different data sources in your application
• Accessing a provider:
• Content providers are Android’s central mechanism that enables you to access data of other applications – mostly information stored in databases or flat files.
• Content providers support the four basic operations, normally called CRUD-operations. 
• Android provides some standard content providers to access contacts, media files, preferences and so on.
• When you want to access data in a content provider, you use the ContentResolver object in your application's Context to communicate with the provider as a client.
• The provider object receives data requests from clients, performs the requested action, and returns the results.
• The ContentResolver methods provide the basic "CRUD" (Create, Retrieve, Update, and Delete) functions of persistent storage. 
  
• Content URIs:
• A content URI is a URI that identifies data in a provider. 
• Content URIs include the symbolic name of the entire provider (its authority) and a name that points to a table (a path). 
• The ContentProvider uses the path part of the content URI to choose the table to access.
• Exa.
  
• Whenever you want to access data from a content provider you have to specify a URI. 
• URIs for content providers look like this: content://authority/optionalPath/optionalId
• They contain four parts:

• The scheme for content providers is always “content”.
• Authorities have to be unique for every content provider. 
• The optional path, is used to distinguish the kinds of data your content provider offers.
• The id is used whenever you want to access a single record.

• Types of URIs:
• There are two types of URIs: 
• Directory and Id-based URIs.
• Note: If no id is specified a URI is automatically a directory-based URI.
• You use directory-based URIs to access multiple elements of the same type (e.g. all songs of a band).
• All CRUD-operations are possible with directory-based URIs.
• You use id-based URIs if you want to access a specific element. 
• You cannot create objects using an id-based URI – but reading, updating and deleting is possible.
• Content Types:
• A content type consist of a media type and a subtype divided by a slash. 
• Exa. “image/png”. 
• The media type “image” describes as an image file which is further specified by the subtype “png”.
• Useful Built-in Android Content Provider:
• Applications can access data within other applications on the Android system through content provider interfaces.
• Android devices ship with a number of built-in applications, many of which expose their data as content providers.
• Your application can access content provider data from a variety of sources.
• You can find the content providers included with Android in the package android.provider.
• Example:
• 1. MediaStore
• 2. CallLog
• 3. Browser
• 4. ContactsContract
• 5. Settings
• 6. UserDictionary
• Figure.
  
• Using the MediaStoreContent Provider:
• You can use the MediaStore content provider to access media on the phone and on external storage devices.
• The primary types of media that you can access are audio, images, and video.
• You can access these different types of media through their respective content provider classes under android.provider.MediaStore.
• You can retrieve, add, and delete media files from the device.
• Exa.
  
• Using the CallLogContent Provider:
• Android provides a content provider to access the call log on the handset via the class android.provider.CallLog.
• You can use the CallLog to filter recently dialed calls, received, and missed calls.
• The CallLog is a useful content provider for customer relationship management (CRM) applications.
• Accessing Content Providers That Require Permissions: android.permission.READ_CONTACTS
• Using the Browser Content Provider:
• The Browser content provider exposes the user’s browser site history and their bookmarked websites.
• You access this con-tent provider via the android.provider.Browser class.
• You might use the Browser content provider to add a bookmark for your application support website.
• Using the Contacts Content Provider:
• People always want phone numbers handy for calling friends, family, co-workers, and clients. 
• Additionally, most phones show the identity of the caller based on the contacts application, including nicknames, photos, or icons.
• Android provides a built-in Contact application, and the contact data is exposed to other Android applications using the content provider interface.
• The content provider for accessing user contacts was originally called Contacts.
• This class, called ContactsContract, includes a sub-class called ContactsContract.Contacts. 
• This is preferred contacts content provider, as of API Level 5.
• Using the UserDictionaryContent Provider:
• You can use this content provider for predictive text input on text fields and other user input mechanisms.
• Individual words stored in the dictionary are weighted by frequency and organized by locale.
• You can use the addWord() method within the UserDictionary.Words class to add words to the custom user dictionary.
• Using the SettingsContent Provider:
• You can use this content provider to access the device settings and user preferences. 
• Settings are organized much as they are in the Settings application—by category.
• You can find information about the Settings content provider in the android.provider.Settings class.